WO2019225433A1

WO2019225433A1 - Fluorine concentration measurement method, fluorine concentration measurement device, water treatment method, and water treatment device

Info

Publication number: WO2019225433A1
Application number: PCT/JP2019/019289
Authority: WO
Inventors: 吉崎　耕大; 俊一池田; 麻未冨田; 郁村上; 幸男樋口; 張本　崇良; 総太岩谷
Original assignee: 株式会社クボタ; クボタ化水株式会社
Priority date: 2018-05-21
Filing date: 2019-05-15
Publication date: 2019-11-28
Also published as: TW202006352A; JPWO2019225433A1; JP7264888B2; TWI811365B

Abstract

A fluorine concentration measurement method comprising the steps of: measuring the potential of sample water with a fluorine ion electrode meter to obtain a potential value P; bringing the sample water into contact with a fluorine adsorbent agent to produce fluorine-removed sample water; adding a fluorine compound to the fluorine-removed sample water to prepare a first standard solution for a fluorine concentration C1; adding a fluorine compound or not adding a fluorine compound to the fluorine-removed sample water to prepare a second standard solution for a fluorine concentration C2; measuring the potential of the first standard solution with a fluorine ion electrode meter to obtain a potential value P1; measuring the potential of the second standard solution with a fluorine ion electrode meter to obtain a potential value P2; prepare a calibration curve that represents the correlation between a fluorine concentration and a potential value employing the fluorine concentrations C1 and C2 and the potential values P1 and P2; and calculating the fluorine concentration of the sample water which corresponds to the potential value P on the basis of the calibration curve.

Description

Fluorine concentration measuring method, fluorine concentration measuring device, water treatment method and water treatment device

The present invention relates to a fluorine concentration measurement method, a water treatment method using the method, a fluorine concentration measurement device, and a water treatment apparatus including the device.

Conventionally, a method for measuring a fluorine ion concentration in a solution using an ion selective electrode is known. For example, Non-Patent Document 1 describes general matters for quantifying ion concentration using an ion electrode, and that the fluorine ion concentration can be obtained by measuring potential using the ion electrode. Membrane potential is generated according to the amount, the activity coefficient fluctuates due to the influence of ionic strength and causes measurement error, and the ionic strength adjustment liquid has a high concentration to keep the ionic strength of the sample water constant. It is described that the electrolyte solution may be added, and the measurement by the ion electrode is affected by the coexisting ions, and therefore it is necessary to take measures to avoid the influence. In Non-Patent Document 2, in order to avoid the influence of coexisting ions in the ion electrode method, a fluorine compound is pretreated and separated by distillation, and a buffer solution (ionic strength adjusting solution) is added to adjust the pH to 5.2 ± 0. It is described that the potential is measured using a fluoride ion selective electrode, and the fluoride ion is quantified. In Non-Patent Document 3, in order to prevent the influence of complex formation by coexisting ions of fluoride ions in the ion electrode method, the addition of sodium citrate or cyclohexanediaminetetraacetic acid causes fluoride ions to complex with Fe or Al. It is described that suppresses. Patent Document 1 discloses a method in which sample water is diluted with water and measured with an ion electrode in order to suppress the influence of coexisting magnesium ions when measuring the fluorine concentration in the sample water by the ion electrode method. .

JP 2011-47768 A

As described above, in the conventional fluorine concentration measurement using a fluorine ion electrode meter, accurate measurement of the fluorine concentration may be difficult due to the influence of coexisting ions, or the pretreatment may be complicated. Further, in the method of diluting sample water with water as described in Patent Document 1, when the amount of coexisting magnesium ions is excessively larger than the amount of fluorine ions, it is necessary to set a high dilution rate. For this reason, it is inevitable that the lower limit of quantification of the fluorine concentration is increased, and it is difficult to accurately measure the fluorine concentration for sample water having a low fluorine concentration, which limits the application.

The present invention has been made in view of the above circumstances, and the purpose thereof is a fluorine concentration measuring method capable of easily or accurately determining or calculating the fluorine concentration in sample water even in the case of sample water containing coexisting ions. And providing a fluorine concentration measuring device. The present invention also provides a water treatment method using the fluorine concentration measuring method of the present invention and a water treatment apparatus equipped with the fluorine concentration measuring device of the present invention.

The fluorine concentration measuring method of the present invention that has solved the above-mentioned problems includes a step of measuring the potential of sample water with a fluorine ion electrode meter to obtain a potential value P, and bringing the sample water into contact with a fluorine adsorbent. A step of obtaining a fluorine-removed sample water, a step of adding a fluorine compound to the fluorine-removed sample water to prepare a reference solution having a fluorine concentration C1, and a step of measuring the potential of the reference solution with a fluorine ion electrode meter to obtain a potential value P1 And a step of comparing the potential value P and the potential value P1 to determine the magnitude relationship between the fluorine concentration of the sample water and the fluorine concentration C1. The fluorine concentration measurement method of the present invention also includes a step of measuring the potential of the sample water with a fluorine ion electrode meter to obtain a potential value P, a step of contacting the sample water with a fluorine adsorbent to obtain a fluorine-removed sample water, A step of preparing a first reference solution having a fluorine concentration C1 by adding a fluorine compound to the fluorine removal sample water, and a step of preparing a second reference solution having a fluorine concentration C2 with or without the addition of the fluorine compound to the fluorine removal sample water. Measuring the potential of the first reference solution with a fluorine ion electrode meter to obtain a potential value P1, measuring the potential of the second reference solution with a fluorine ion electrode meter to obtain the potential value P2, and fluorine concentration Using C1, C2 and potential values P1, P2, a step of creating a calibration curve representing the correlation between the fluorine concentration and the potential value, and calculating the fluorine concentration of the sample water corresponding to the potential value P based on the calibration curve Process It may have a.

According to the fluorine concentration measuring method of the present invention, sample water is brought into contact with a fluorine adsorbent to prepare a fluorine-removed sample water, and a fluorine compound is added thereto to prepare a reference solution. Except for the components, they have almost the same composition (matrix). Therefore, the sample water and the reference solution are compared and measured between solutions having the same matrix, and the potential measurement value is basically a function of only the fluorine concentration. Therefore, according to the fluorine concentration measuring method of the present invention, even when a large amount of coexisting ions are present in the sample water, an accurate calibration curve can be created using the reference solution corresponding to the sample water. . In addition, since the potential is measured using a fluorine ion electrode meter, simple and rapid measurement is possible.

In the step of preparing the reference solution, it is preferable to use a fluorine standard solution with a known fluorine concentration as the fluorine compound added to the fluorine-removed sample water. Thereby, a reference solution having a desired fluorine concentration can be easily prepared.

In the step of obtaining the potential value P, the fluorine removal standard solution after contacting the fluorine standard solution with the fluorine adsorbent may be added to the sample water, and the potential of the obtained solution may be measured with a fluorine ion electrode meter.

The sample water preferably has an ionic strength of 0.05 mol / L to 3.5 mol / L. According to the present invention, it is possible to accurately measure the fluorine ion concentration even with sample water having such ionic strength. As sample water, for example, flue gas desulfurization waste water discharged from flue gas desulfurization equipment can be used.

The present invention also provides a fluorine concentration measuring device. A fluorine concentration measuring apparatus according to the present invention includes a measuring unit provided with a fluorine ion electrode meter, a first supply means for supplying sample water to the measuring unit, a fluorine removing unit in which a fluorine adsorbent is disposed, and a fluorine removing unit. Second supply means for supplying sample water, fluorine compound supply means for adding a fluorine compound to fluorine removal sample water discharged from the fluorine removal section and supplying a reference liquid, and supplying fluorine removal sample water or reference liquid to the measurement section It has a 3rd supply means and the calculating part which calculates the value or magnitude relationship of the fluorine concentration in sample water from the electric potential value of sample water and a reference | standard solution measured by the measurement part. By using the fluorine concentration measuring apparatus of the present invention, the fluorine concentration in the sample water can be determined or calculated simply and accurately.

The fluorine concentration measuring device may further include a mixing unit that prepares the reference solution by mixing the fluorine-removed sample water discharged from the fluorine-removing unit and the fluorine compound supplied from the fluorine compound supplying unit. The mixing unit may be provided in a flow path communicating with the outlet side of the fluorine removing unit.

The fluorine concentration measuring device may be provided with a first measuring unit for analyzing sample water and a second measuring unit for analyzing the reference solution as measuring units. In this case, the first supply unit supplies sample water to the first measurement unit, and the third supply unit supplies fluorine removal sample water or a reference solution to the second measurement unit. Thus, if the first measurement unit for analyzing the sample water and the second measurement unit for analyzing the reference solution are provided, the fluorine concentration of the sample water can be determined or calculated more quickly.

The fluorine concentration measuring apparatus further includes a water intake unit that receives sample water, and the first supply channel that communicates with the water intake unit and the inlet side of the measurement unit is provided as the first supply unit, and the second supply is provided. As a means, it is preferable that a second supply flow path communicating with the intake portion and the inlet side of the fluorine removing portion is provided. By providing the water intake portion in this way, the sample water and the reference solution can be derived from the same source.

As the fluorine compound, it is preferable to use a fluorine standard solution having a known fluorine concentration. In this case, the fluorine concentration measuring device further supplies a fluorine adsorbent, a second fluorine removing unit to which a fluorine standard solution is supplied, and a fluorine removing standard solution discharged from the second fluorine removing unit to the measuring unit. You may have a 4th supply means.

The present invention also provides a water treatment method combined with the fluorine concentration measuring method of the present invention. The water treatment method of the present invention is, for example, a water treatment method for obtaining treated water by removing at least a part of fluorine ions from fluorine ion-containing water, and the treated water is used as sample water by the fluorine concentration measuring method of the present invention. Measures the fluorine concentration in the treated water. The water treatment method of the present invention is a water treatment method in which a chemical is added to fluorine ion-containing water to remove at least a part of the fluorine ions, and the fluorine ion-containing water is converted into sample water by the fluorine concentration measurement method of the present invention. Alternatively, the fluorine concentration in the fluorine ion-containing water may be measured, and the amount of the drug added to the fluorine ion-containing water may be determined based on the measurement result. The water treatment method of the present invention is a water treatment method in which fluorine ion-containing water is introduced into a fluorine adsorption tower filled with a fluorine adsorbent, and at least part of the fluorine ions is removed. A method may be used in which fluorine ion-containing water is used as sample water, the fluorine concentration in fluorine ion-containing water is measured, and fluorine ion-containing water is diluted based on the measurement result.

The present invention also provides a water treatment apparatus that obtains treated water by removing at least part of fluorine ions from fluorine ion-containing water, and also includes a water treatment apparatus equipped with the fluorine concentration measuring apparatus of the present invention.

According to the fluorine concentration measuring method and fluorine concentration measuring apparatus of the present invention, the fluorine ion concentration in the sample water can be determined or calculated easily and accurately even if the sample water contains a large amount of coexisting ions.

The flowchart of the fluorine concentration measuring method of this invention is represented. The calibration curve created according to the fluorine concentration measuring method of the present invention, and the graph plotting the potential values of sample water having various fluorine concentrations and the measurement results of the fluorine concentration are plotted. The structural example of the fluorine concentration measuring apparatus of this invention is represented. The structural example of the fluorine concentration measuring apparatus of this invention is represented. The structural example of the fluorine concentration measuring apparatus of this invention is represented. The structural example of the fluorine concentration measuring apparatus of this invention is represented. The structural example of the water treatment apparatus of this invention is represented.

The fluorine concentration measuring method of the present invention will be described with reference to FIG. FIG. 1 shows a flow chart of the fluorine concentration measuring method of the present invention. The fluorine concentration measuring method of the present invention includes a step of measuring the potential of sample water with a fluorine ion electrode meter to obtain a potential value P (sample water measuring step), and contacting the sample water with a fluorine adsorbent to remove fluorine from the sample water. (Fluorine removal step), a step of preparing a reference solution with a clear fluorine concentration by adding a fluorine compound to the fluorine-removed sample water (reference solution preparation step), and the potential of the reference solution as a fluorine ion electrode meter And a step of determining or calculating the fluorine concentration of the sample water from the measured value of the potential value obtained from the step of obtaining the potential value P1 (reference solution measuring step) and the sample water measuring step and the reference solution measuring step ( Fluorine concentration determination / calculation step). According to the fluorine concentration measuring method of the present invention, the fluorine ion concentration in the sample water can be determined easily and accurately. In the present specification, “fluorine ion” is used synonymously with “fluoride ion”, and “fluorine concentration” means “fluorine ion concentration”.

The type of sample water used for measurement is not particularly limited, and may contain fluorine ions or may not contain fluorine ions. For example, when various industrial wastewaters such as industry, agriculture, and fishery, process wastewater, and domestic wastewater are used as sample water, the sample water may contain fluoride ions. Conversely, when the treated water of these wastewaters is used as sample water, the sample water may not contain fluorine ions. In addition, environmental water such as river water, lake water, ground water, seawater and the like may be used as sample water.

Sample water containing components other than fluorine ions is allowed, and any coexisting ions may be contained in any amount. In the measurement of fluoride ion concentration with a fluoride ion electrode meter, it is usually necessary to consider these coexisting ions because the potential value changes due to the influence of the coexisting ions, or the coexisting ions can act as an inhibitor when detecting fluoride ions. Become. For example, since the potential value measured with a fluorine ion electrode meter is affected by the ionic strength in the sample water, an ionic strength adjusting agent (a salt of a strong electrolyte unrelated to ion measurement) may be added to suppress this effect. It is necessary. In addition, when metal components such as magnesium ions, aluminum ions, iron ions, and calcium ions are contained in a large amount in the sample water, the measured value by the fluorine ion electrode meter decreases due to complex formation of fluorine ions with these metal components. Therefore, it may be necessary to add a chemical for suppressing the complex formation of fluorine ions. However, in the present invention, such coexisting ions may be contained in the sample water, and even if coexisting ions that affect the measurement of the fluorine ion electrode meter are present in the sample water, the fluorine ion concentration in the sample water Can be obtained accurately.

For example, in coal-fired power plants, coke factories, steel factories, etc., exhaust gas containing sulfur and fluorine is emitted by burning coal and coke, but when the exhaust gas is desulfurized by flue gas desulfurization equipment Then, flue gas desulfurization wastewater containing high concentration of fluoride ions along with sulfate ions is generated. As a desulfurization method in the flue gas desulfurization equipment, a wet treatment method using magnesium hydroxide, sodium hydroxide, or calcium hydroxide is known. When these metal hydroxides are used as a desulfurization agent, fluorine ions are used. As a result, flue gas wastewater containing high concentrations of sulfate ions and metal ions (magnesium ions, sodium ions and calcium ions) is generated. Normally, it is difficult to measure the fluorine concentration in such flue gas treatment wastewater with a fluorine ion electrode meter, but according to the present invention, even if the flue gas desulfurization wastewater discharged from the flue gas desulfurization equipment is used as sample water, The fluorine concentration in the waste water can be accurately measured. Furthermore, examples of the wastewater containing coexisting ions that affect the measurement value by the fluorine ion electrode meter together with the fluorine ions include scrubber wastewater discharged from the optical fiber manufacturing facility. According to the present invention, even when such scrubber wastewater is used as sample water, the fluorine concentration can be accurately determined.

イオン The ionic strength of the sample water to be measured is not particularly limited. Conventionally, it has been difficult to measure the fluorine concentration with a fluorine ion electrode meter when a large amount of metal components capable of complexing with fluorine ions is contained. According to the present invention, the measurement of the fluorine ion concentration can be performed even in such sample water. Is possible. Therefore, from such a viewpoint, the ionic strength of the sample water may be, for example, 0.05 mol / L to 3.5 mol / L. Of course, in the present invention, it is also possible to measure the fluorine concentration of sample water having a lower ionic strength or higher ionic strength.

Sample water may be pH adjusted as necessary prior to the sample water measurement step and the fluorine removal step. The pH of the sample water is preferably 2.0 or more, more preferably 2.5 or more, further preferably 2.8 or more, more preferably 7.0 or less, more preferably 6.0 or less, and further preferably 5.0 or less. Preferably, 4.0 or less is even more preferable. If the pH of the sample water is within such a range, the fluorine ions in the sample water are likely to exist in a free state, and the fluorine ions are preferably easily adsorbed and removed by the adsorbent in the fluorine removal step. Therefore, when the pH of the sample water is outside the above range, it is preferable to add an acid or an alkali to adjust the pH to the range.

Sample water may be diluted with water as necessary prior to the sample water measurement step and the fluorine removal step. For example, when the pH of the sample water is extremely high or extremely low, or when the coexisting ion concentration of the sample water is extremely high, the sample water may be appropriately diluted with water. For example, if the coexisting ion concentration in the sample water is extremely high, it will take time to remove the fluorine ions when the sample water is brought into contact with the fluorine adsorbent in the fluorine removal process, or the fluorine ions will not be sufficiently removed. Therefore, the fluorine removal process may be accelerated by diluting with water. Even if the sample water is diluted with water, it is preferable to suppress the dilution rate as much as possible. This enables the sample water having a lower fluorine concentration to be quantified. Therefore, when the sample water is diluted with water, for example, it is not necessary to dilute the sample water to such an extent that the complexed metal component and fluorine ions are liberated.

In the sample water measurement step, the potential of the sample water is measured with a fluorine ion electrode meter, and a potential value P is obtained. As the fluorine ion electrode meter, a known fluorine ion electrode meter may be used, and one having a fluorine ion electrode that generates a potential corresponding to the fluorine ion concentration (activity) in the solution can be used. By combining a membrane electrode equipped with a fluorine ion selective membrane and a reference electrode (reference electrode) to form a battery and measuring its electromotive force, the potential value corresponding to the fluorine ion concentration (activity) in the solution can be obtained. can get. The measured potential value P can be displayed or stored on the ion concentration meter by connecting a fluorine ion electrode meter to the ion concentration meter, for example.

The potential value P obtained in the sample water measurement step is a value affected by the coexisting ions in the sample water. Therefore, this potential value P cannot be directly converted into a fluorine concentration value in the sample water. Therefore, in the present invention, a reference solution is separately prepared in the fluorine removal step and the reference solution preparation step, the potential value of the reference solution is measured in the reference solution measurement step, and the potential value P of the sample water is determined in the fluorine concentration determination / calculation step. By comparison, the fluorine concentration of the sample water is obtained.

In the fluorine removal step, sample water derived from the same as that used for measuring the potential value P is brought into contact with a fluorine adsorbent to obtain fluorine removal sample water. The sample water used for the fluorine removal step may be the same batch as the sample water used for the sample water measurement step or may be a different batch. In the former case, for example, a part of sample water collected in one batch is used for the sample water measurement process, and the other part is used for the fluorine removal process. Or you may use for the fluorine removal process the sample water which measured the electric potential at the sample water measurement process. In the latter case, for example, after sample water used for the sample water measurement step is collected, sample water used for the fluorine removal step may be collected, and vice versa. Basically, the sample water for the sample water measurement process and the sample water for the fluorine removal process are collected with a time difference as close as possible (for example, preferably within 30 minutes, more preferably within 15 minutes, and even more preferably within 10 minutes). However, if the variation with time of the composition of the sample water is small, the time difference may be increased to some extent.

As the fluorine adsorbent, a known adsorbent capable of adsorbing fluorine ions may be used. For example, an alumina adsorbent, a ferrite iron adsorbent, a zirconium adsorbent, a cerium adsorbent, or the like may be used. it can. Among them, it is preferable to use a zirconium-based adsorbent or a cerium-based adsorbent as an adsorbent that can highly adsorb and remove fluorine ions. Examples of the zirconium-based adsorbent include adsorbents containing zirconium oxide (ZrO ₂ ), particularly hydrous zirconium oxide (ZrO ₂ .nH ₂ O). Examples of the cerium-based adsorbent include adsorbents containing cerium oxide (CeO ₂ ), particularly hydrous cerium oxide (CeO ₂ · nH ₂ O). These adsorbents contain a resin, and zirconium oxide, cerium oxide or the like may be fixed or reinforced by the resin.

The contact between the sample water and the fluorine adsorbent may be carried out in a tank or by passing through an adsorption column. When the sample water and the fluorine adsorbent are brought into contact with each other in the tank, for example, the fluorine adsorbent may be added to the sample water held in the tank. At this time, the fluorine adsorbent may be brought into contact with the sample water as it is, or a predetermined bag is provided so that a permeable bag containing the fluorine adsorbent is immersed in the sample water or the fluorine adsorbent can be handled integrally. A product formed into the shape may be immersed in sample water. The addition amount of the fluorine adsorbent at this time may be appropriately set within a range of 1 g / L to 100 g / L, for example, with respect to 1 L of sample water. The addition amount of the fluorine adsorbent may be appropriately set according to the expected fluorine concentration of the sample water. Even if the fluorine ions in the sample water fluctuate within the expected range, 95% or more of the fluorine ions is 3 It is preferable to make the addition amount that can be removed by adsorption within minutes. Of course, it is good also as the quantity of adsorption agent which can achieve a high adsorption rate in a shorter time than this. The contact time between the sample water and the fluorine adsorbent is preferably set appropriately from 15 seconds to 10 minutes (more preferably from 30 seconds to 5 minutes) from the viewpoint of promptly measuring the fluorine concentration.

When contacting the sample water and the fluorine adsorbent in the adsorption column, the sample water may be passed through the adsorption column filled with the fluorine adsorbent. The sample water may be passed through the adsorption column in an upward flow, may be passed in a downward flow, or may be passed in a lateral flow. In these cases, the pipe line may be filled with an adsorbent and used as an adsorption column. The amount of the fluorine adsorbent packed into the adsorption column is, for example, an amount that allows 95% or more of the fluorine ions to be adsorbed and removed when sample water is passed at a space velocity (SV) of 20 hr ^−1. preferable. Of course, it is good also as the quantity of adsorbent which can achieve a high adsorption rate with a space velocity faster than this. Liquid permeation speed of the adsorption column of the sample water, as a space velocity (SV), for example in the range of 6hr ^{^-1} ~ 180hr ^-1 (more preferably in the range of 12hr ^{^-1} ~ 120hr ^-1) be set appropriately preferable.

Fluorine-removed sample water from which fluorine ions have been removed from the sample water is obtained by bringing the sample water into contact with a fluorine adsorbent in the fluorine removal step. Note that the fluorine ion concentration of the fluorine-removed sample water may not be completely 0 mg / L. The fluorine ion concentration of the fluorine-removed sample water is, for example, preferably 3 mg / L or less, more preferably 2 mg / L or less, further preferably 1 mg / L or less, particularly preferably 0.5 mg / L or less. Or it is preferable that the fluorine ion removal rate in a fluorine removal process will be 95% or more, 97% or more is more preferable, and 99% or more is further more preferable. Basically, in obtaining the fluorine concentration of the sample water, it is only necessary to reduce the fluorine ion concentration of the fluorine-removed sample water to such an extent that sufficient accuracy (for example, error ± 5% or less) is obtained.

Fluorine-removed sample water obtained in the fluorine removal step is then prepared by adding a fluorine compound in the reference solution preparation step to prepare a reference solution. The type of fluorine compound added in the preparation of the reference solution is not particularly limited, but an alkali metal salt of fluorine is preferable and sodium fluoride is more preferable from the viewpoint of excellent solubility in water and easy availability. The fluorine compound may be added to the fluorine-removed sample water as a solid, or may be added to the fluorine-removed sample water as a solution. The fluorine compound is preferably added as a solution to the fluorine-removed sample water, whereby a reference solution in which fluorine ions are dissolved at a predetermined concentration can be easily prepared. In this case, the addition amount of the fluorine compound solution is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and further preferably 1 part by mass or less with respect to 100 parts by mass of the fluorine-removed sample water. That is, it is preferable to appropriately adjust the fluorine concentration of the fluorine compound solution so as to achieve such an addition amount.

In the reference liquid preparation step, it is preferable to prepare a fluorine compound solution having a predetermined concentration in advance and adjust the amount of the fluorine compound solution added according to the fluorine concentration of the reference solution. It can be easily prepared. As such a fluorine compound solution, it is convenient to use a fluorine standard solution having a known fluorine concentration. The fluorine compound solution or the fluorine standard solution may contain a pH buffering agent or the like.

In the reference solution preparation step, a reference solution having a fluorine concentration C1 is prepared. When the fluorine concentration C1 of the reference solution is used for determination of the magnitude relationship with the fluorine concentration of the sample water, for example, the fluorine concentration used as a reference for the sample water (for example, the emission standard value set by the Ministry of the Environment, fluorine treatment) At this time, the upper limit value of fluorine concentration in the specification of the processing equipment or a value obtained by multiplying these values by a safety factor may be set. The fluorine concentration C1 of the reference solution is conveniently set to a value obtained by dividing the fluorine concentration of the added fluorine compound, that is, the F amount (mass or molar amount) of the added fluorine compound by the volume of the reference solution.

In the reference solution preparation step, a first reference solution having a fluorine concentration C1 may be prepared and a second reference solution having a fluorine concentration C2 may be prepared. The fluorine concentration C1 of the first reference solution and the fluorine concentration C2 of the second reference solution may be set to, for example, a fluorine concentration that serves as a reference for sample water, or may be set appropriately to a fluorine concentration that is appropriate for the creation of a calibration curve. You can also. The second reference solution may be adjusted to a fluorine concentration C2 by adding a fluorine compound to the fluorine removal sample water, or adjusted to a fluorine concentration C2 without adding a fluorine compound to the fluorine removal sample water. May be. In the latter case, the fluorine concentration of the second reference solution is 0 mg / L or a value close to it (for example, 1 mg / L). In the reference solution preparation step, a third reference solution having a fluorine concentration C3, a fourth reference solution having a fluorine concentration C4, or the like may be further prepared.

The reference solution obtained in the reference solution preparation step preferably has a pH of 2.0 or higher, more preferably 2.5 or higher, further preferably 2.8 or higher, more preferably 7.0 or lower, and 6.0 or lower. More preferably, 5.0 or less is more preferable, and 4.0 or less is even more preferable. When the pH of the reference solution is out of the range, it is preferable to adjust the pH to the range by adding acid or alkali to the reference solution or the fluorine-removed sample water. The difference between the pH of the reference solution for measuring the potential value with the fluorine ion electrode meter and the pH of the sample water for measuring the potential value with the fluorine ion electrode meter is preferably not so large, and the difference between the two is preferably within 2.0 1.5 or less is more preferable, and 1.0 or less is more preferable.

In the reference solution preparation process, a reference solution is prepared by adding a fluorine compound to the fluorine-removed sample water. However, the reference solution obtained by adding a cation component derived from the fluorine compound to the original sample water. It will be the shape that has been. Therefore, from the viewpoint of strictly aligning the ionic strength and coexisting ionic components of the sample water and the reference solution, the cation hydroxide of the fluorine compound added to the fluorine-removed sample water is added to the sample water prior to the sample water measurement step. Also good. The amount of the cation hydroxide added at this time is preferably the cation equivalent amount of the fluorine compound added to the fluorine-removed sample water. When adding a pH buffering agent in the reference solution preparation step, the same amount of pH buffering agent may be added to the sample water prior to the sample water measurement step. When adding a fluorine compound solution (for example, fluorine standard solution) to the fluorine-removed sample water, add the fluorine compound solution (for example, fluorine standard solution) brought into contact with the fluorine adsorbent to the sample water. The potential may be measured by a fluorine ion electrode meter to obtain the potential value P. In this case, a fluorine compound solution from which fluorine ions have been removed or a fluorine standard solution from which fluorine ions have been removed (for example, a fluorine removal standard solution) is added to the sample water. Normally, the fluorine concentration of the sample water can be measured with sufficiently high accuracy without strictly aligning the ionic strength and coexisting ion components of the sample water and the reference solution.

Subsequent to the reference solution preparation step, in the reference solution measurement step, the potential of the reference solution is measured with a fluorine ion electrode meter. In the reference solution measurement step, the potential of the reference solution can be measured with a fluorine ion electrode meter in the same manner as the sample water measurement step described above. The fluorine ion electrode meter used for measuring the reference solution may be the same as or different from the fluorine ion electrode meter used for measuring the sample water. In the reference liquid measurement step, a potential value P1 is obtained as the potential value of the (first) reference liquid having a fluorine concentration C1. When the second reference solution having a fluorine concentration C2 is prepared in the reference solution preparation step, the potential value P2 is obtained as the potential value of the second reference solution in the reference solution measurement step. Similarly, when the third reference solution having a fluorine concentration C3 and the fourth reference solution having a fluorine concentration C4 are prepared in the reference solution preparing step, the potential value P3 is obtained as the potential value of the third reference solution in the reference solution measuring step. Thus, the potential value P4 is obtained as the potential value of the fourth reference solution.

Next, in the fluorine concentration determination / calculation step, the fluorine concentration of the sample water is determined or calculated from the measured value of the potential value obtained from the sample water measurement step and the reference solution measurement step. When determining the fluorine concentration of the sample water, the potential value P of the sample water is compared with the potential value P1 of the (first) reference solution of the fluorine concentration C1, and the magnitude relationship between the fluorine concentration of the sample water and the fluorine concentration C1 is determined. judge. At this time, if the potential value P is larger than the potential value P1, it is judged that the fluorine concentration of the sample water is smaller than C1, and if the potential value P is smaller than the potential value P1, the fluorine concentration of the sample water is larger than C1. It can be judged that it is large. The determination of the magnitude relation of the fluorine concentration of the sample water may also be performed for the fluorine concentration C2 of the second reference solution, and for the fluorine concentration C3 of the third reference solution and the fluorine concentration C4 of the fourth reference solution. You may also go.

When calculating the specific value of the fluorine concentration of the sample water, prior to the fluorine concentration determination / calculation step, the correlation between the fluorine concentration and the potential value is expressed from the fluorine concentrations C1, C2 and the potential values P1, P2. A step of creating a calibration curve (calibration curve creation step) is performed. In preparing the calibration curve, the horizontal axis represents the potential value, the vertical axis represents the logarithmic value of the fluorine concentration, the fluorine concentration C1 and potential value P1 of the first reference solution, and the fluorine concentration C2 and potential value of the second reference solution. A calibration curve can be created by plotting P2 and linear approximation. From the viewpoint of creating a more accurate calibration curve, it is preferable to further plot the fluorine concentration C3 and potential value P3 of the third reference solution, and further plot the fluorine concentration C4 and potential value P4 of the fourth reference solution. More preferred.

FIG. 2 is a graph showing the relationship between the potential value and the fluorine concentration for the calibration curve created in this way and the results of measuring the sample water having various fluorine concentrations. First, five kinds of reference solutions having MgSO ₄ concentration of 60,000 mg / L, pH 5.4, fluorine concentration of 1 mg / L, 10 mg / L, 25 mg / L, 50 mg / L, and 100 mg / L were prepared. A calibration curve was created by measuring the value and plotting the relationship between the potential value and the fluorine concentration (logarithmic value). Next, sample water having an MgSO ₄ concentration of 60,000 mg / L and pH 5.4 and an arbitrary fluorine concentration was prepared, and the relationship between the potential value and the measured value of the fluorine concentration was plotted. As shown in FIG. 2, the calibration curve shows good linearity in the relationship between the potential value and the fluorine concentration (logarithmic value), and it can be seen that the measured value of the sample water having an arbitrary fluorine concentration is also on the calibration curve.

According to the fluorine concentration measurement method of the present invention, fluorine ions are removed from sample water to prepare a fluorine-removed sample water, and a reference compound is prepared by adding a fluorine compound to the sample water. Except for, it has substantially the same composition (matrix). That is, the sample water and the reference solution have almost the same type and concentration of coexisting ions except for the presence or absence of fluorine ions, and the ionic strength is the same except for the fluorine component. Even if there is a component that can form a complex with fluoride ions in the sample water and the reference solution, the type and concentration of the component are the same in the sample water and the reference solution. The degree of influence is about the same. Therefore, the sample water and the reference solution are compared and measured between solutions having the same matrix, and the potential measurement value is basically a function of only the fluorine concentration. Therefore, according to the fluorine concentration measurement method of the present invention, even if a large amount of coexisting ions exist in the sample water, an accurate calibration curve can be created using a reference solution corresponding to the sample water, Can be determined. In addition, since the potential is measured using a fluorine ion electrode meter, simple and rapid measurement is possible.

When the present inventors examined the influence of the coexisting ions on the measured fluorine concentration, for example, the same fluorine ion concentration, one containing no magnesium sulfate and the other containing 60,000 mg of magnesium sulfate. When the fluorine concentration of each of the two solutions containing / L was measured using a fluorine ion electrode meter, the fluorine concentration of the solution containing magnesium sulfate was the same as that of the solution containing no magnesium sulfate. The measured value was about 1/10. This means that when a calibration curve is prepared using a fluorine standard solution as usual and the fluorine ion concentration is measured using a fluorine ion electrode meter, the solution containing 60,000 mg / L of magnesium sulfate is used. It means that the fluorine concentration measurement value is about 1/10 of the actual value. On the other hand, according to the fluorine concentration measuring method of the present invention, since the matrix of the reference solution used for preparing the calibration curve is the same as the matrix of the sample water, a calibration curve taking the influence of coexisting ions into consideration is created, It is possible to accurately measure the fluorine concentration of water.

When preparing the reference solution, if the ion exchange reaction between fluoride ions and hydroxide ions occurs by bringing the sample water into contact with the fluorine adsorbent, the pH of the reference solution will be higher than the pH of the sample water. However, it was found that the effect of pH difference on the measured fluorine concentration was very small compared to the effect of coexisting ions. In particular, in the case of sample water containing a large amount of coexisting ions, the change in pH value tended to be smaller due to the pH buffering action of the coexisting ions. From the viewpoint of suppressing the influence of the difference in pH as much as possible, the difference in pH between the sample water and the reference solution is preferably within 2.0, more preferably within 1.5, and even more preferably within 1.0.

The measurement of potential value with a fluorine ion electrode meter is slightly affected by temperature. From the viewpoint of eliminating the influence of the potential measurement temperature as much as possible, the temperature difference between the sample water and the reference solution in the potential measurement is preferably within 30 ° C, more preferably within 20 ° C, and even more preferably within 10 ° C. .

The method for measuring the fluorine concentration of the present invention shows a particularly excellent effect when there are many coexisting ions other than fluorine ions in the sample water. In such a case, more accurate measurement of the fluorine ion concentration is possible. From such a viewpoint, in the present invention, it is preferable to use sample water having an ionic strength of 0.05 mol / L or more as a measurement target.

The fluorine concentration measuring method of the present invention has been described above. However, when the fluorine concentration measuring method of the present invention is applied to the measurement of fluorine concentration in water to be treated (raw water) of a water treatment method using a fluorine adsorbent. As the fluorine removal sample water, treated water obtained by bringing treated water into contact with the fluorine adsorbent can be used, and a reference compound can be prepared by adding a fluorine compound thereto. Also in this case, the sample water (treated water) and the reference solution have the same origin, and both have substantially the same matrix. Therefore, the fluorine concentration of sample water can be determined by the fluorine concentration measuring method of the present invention.

Next, the fluorine concentration measuring apparatus of the present invention will be described with reference to FIGS. In addition, in the following description, the description which overlaps with said description is abbreviate | omitted. If the fluorine concentration measuring apparatus of the present invention is used, the fluorine concentration measuring method of the present invention can be suitably implemented. First, the fluorine concentration measuring apparatus shown in FIG. 3 will be described.

The fluorine concentration measuring device includes a measuring unit 1 having a fluorine ion electrode meter 2, a first supply unit 4 for supplying sample water to the measuring unit 1, a fluorine removing unit 5 in which a fluorine adsorbent is disposed, and fluorine removal. A second supply unit 6 for supplying sample water to the unit 5; a fluorine compound supply unit 7 for adding a fluorine compound to the fluorine-removed sample water discharged from the fluorine removing unit 5 to provide a reference solution; and a fluorine-removed sample water or a reference solution Having a third supply means 9 for supplying the measuring unit 1 to the measuring unit 1 and a calculating unit 10 for calculating the value of fluorine concentration in the sample water or the magnitude relationship from the potential value of the sample water and the reference solution measured by the measuring unit 1 It is.

The measuring unit 1 is equipped with a fluorine ion electrode meter 2 and holds an analysis target liquid whose potential is measured by the fluorine ion electrode meter 2. The above description is referred to for details of the fluorine ion electrode meter. The fluorine ion electrode meter 2 can communicate information with the calculation unit 10 via wire or wireless. In FIG. 3, the measuring unit 1 includes a tank 3 in which an analysis target liquid is held and a fluorine ion electrode meter 2 provided in the tank 3, and the tank 3 is an analysis target liquid (discharged liquid 11) after potential measurement. A discharge portion for discharging the gas. The measuring unit 1 may be composed of a flow path for an analysis target liquid (specifically, sample water or a reference liquid) and an electrode meter provided in the flow path.

Fluorine adsorbent is disposed in the fluorine removing unit 5. The above description is referred to for details of the fluorine adsorbent. In FIG. 3, the fluorine removal unit 5 is configured as an adsorption column filled with a fluorine adsorbent. The fluorine removing unit 5 may be an adsorption tank in which a fluorine adsorbent is arranged or a pipe line in which a fluorine adsorbent is arranged.

The first supply means 4 supplies sample water to the measuring unit 1 as an analysis target liquid. The second supply means 6 supplies sample water to the fluorine removing unit 5. The above description is referred to for details of the sample water. The 1st supply means 4 and the 2nd supply means 6 will not be specifically limited if sample water can be supplied to the measurement part 1 or the fluorine removal part 5, for example, the flow path through which sample water passes, and liquid feeding to the said flow path The thing provided with the pump, the container which conveys sample water, etc. are mentioned. In FIG. 3, the first supply means 4 is shown as a flow path communicating with the measuring section 1, and the second supply means 6 is shown as a flow path communicating with the entry side of the fluorine removing section 5. May be equipped with a liquid feed pump.

The third supply means 9 is shown in FIG. 3 as supplying the fluorine removal sample water discharged from the fluorine removal unit 5 to the measurement unit 1. The third supply means 9 is not particularly limited as long as it can supply the fluorine-removed sample water or the reference liquid to the measuring unit 1, and for example, a flow path through which the fluorine-removed sample water or the reference liquid passes, or a liquid feed pump through the flow path And a container for transporting the fluorine-removed sample water or reference liquid. In FIG. 3, the 3rd supply means 9 is shown as a flow path connected with the exit side of the fluorine removal part 5, and the measurement part 1, and a fluorine removal sample water flows into the said flow path.

Fluorine compound supply means 7 supplies the fluorine compound to the fluorine-removed sample water. The reference solution is prepared by adding the fluorine compound to the fluorine-removed sample water. For the details of the fluorine compound and the reference solution, the above description is referred to.

The fluorine compound supply means 7 is not particularly limited as long as it can supply a solution or a solid fluorine compound. For example, a flow path through which the fluorine compound solution passes, a liquid flow pump provided in the flow path, a fluorine compound And a container for conveying a fluorine compound. The fluorine compound is supplied from the fluorine compound supply means 7 to, for example, a flow path through which the fluorine-removed sample water passes, a tank in which the fluorine-removed sample water is temporarily stored, and the tank 3 of the measuring unit 1. In FIG. 3, the fluorine compound solution is stored in the storage tank 8, and the fluorine compound solution is supplied from the storage tank 8 to the tank 3 of the measuring unit 1 by the fluorine compound supply means 7. The fluorine compound solution supplied to the tank 3 by the fluorine compound supply means 7 is mixed with the fluorine-removed sample water in the tank 3. As the fluorine compound solution, it is convenient to use a fluorine standard solution having a known fluorine concentration. In this case, the fluorine compound supply unit 7 serves as a fluorine standard solution supply unit.

In the fluorine concentration measuring apparatus shown in FIG. 3, first, sample water is supplied to the tank 3 of the measurement unit 1 by the first supply unit 4, and the potential of the sample water is measured by the fluorine ion electrode meter 2 to obtain the potential value P. . The obtained potential value P is temporarily stored in the calculation unit 10. When the potential measurement of the sample water is finished, the sample water is discharged from the tank 3. On the other hand, the sample water is supplied to the fluorine removing unit 5 by the second supply means 6, and the fluorine ions in the sample water are removed. The fluorine-removed sample water discharged from the fluorine removing unit 5 is transferred to the tank 3 of the measuring unit 1 by the third supply means 9. Fluorine compound is added to the fluorine-removed sample water stored in the tank 3 by the fluorine compound supply means 7, and a (first) reference solution having a fluorine concentration C1 is prepared in the tank 3. The potential of the (first) reference solution is measured by the fluorine ion electrode meter 2 to obtain a potential value P1. The obtained potential value P1 is stored in the calculation unit 10. At this time, the set value of the fluorine concentration C1 of the (first) reference solution is input to the calculation unit 10 or the control of the fluorine compound supply unit 7 is performed by the calculation unit 10 so that the set amount of fluorine compound is the fluorine compound supply unit 7. May be supplied. By comparing the potential value P of the sample water thus obtained with the potential value P1 of the (first) reference solution by the calculation unit 10, the fluorine concentration C1 of the (first) reference solution of the fluorine concentration of the sample water. The magnitude relationship with respect to can be determined.

In the above description, the potential of the sample water is measured by the fluorine ion electrode meter 2, and after obtaining the potential value P, the sample water is discharged from the tank 3. However, the sample water discharged from the tank 3 is removed by fluorine. You may supply to the part 5. In this case, the 2nd supply means 6 is provided as a flow path connected to the exit side (discharge part of the tank 3) of the measurement part 1 and the entrance side of the fluorine removal part 5, for example. A pump may be provided.

In the fluorine concentration measuring apparatus shown in FIG. 3, after measuring the potential of the first reference solution, a fluorine compound may be further added to the first reference solution by the fluorine compound supply means 7 to prepare a second reference solution. Alternatively, the second reference solution may be prepared without adding a fluorine compound to the first reference solution before measuring the potential of the first reference solution. In this case, the potential of the second reference solution is measured by the fluorine ion electrode meter 2 to obtain the potential value P2. The obtained potential value P2 is stored in the calculation unit 10. At this time, the set value of the fluorine concentration C2 of the second reference solution is input to the calculation unit 10 or the calculation of the fluorine compound supply unit 7 is performed by the calculation unit 10 so that a set amount of the fluorine compound is supplied by the fluorine compound supply unit 7. You may be made to do. The calculation unit 10 creates a calibration curve representing the relationship between the fluorine concentration and the potential value from the potential value P1 of the first reference solution and the potential value P2 of the second reference solution thus obtained. A fluorine concentration value corresponding to the potential value P of the sample water can be calculated.

Other structural examples of the fluorine concentration measuring apparatus of the present invention will be described with reference to FIGS. In the description of FIG. 4 to FIG. 6, the description overlapping with FIG. 3 is omitted.

The fluorine concentration measuring apparatus shown in FIG. 4 has a water intake unit 12 that receives sample water, and a first supply channel that communicates with the water intake unit 12 and the inlet side of the measurement unit 1 is provided as the first supply unit 4. As the second supply means 6, a second supply flow path communicating with the water intake unit 12 and the inlet side of the fluorine removing unit 5 is provided. A liquid feed pump may be provided in the first supply channel and / or the second supply channel. By providing the water intake unit 12 in this way, the reference liquid that is the target of potential measurement in the reference liquid measurement process is completely derived from the sample water that is the target of potential measurement in the sample water measurement process. it can.

4 is also provided with a mixing unit 13 for mixing the fluorine removal sample water discharged from the fluorine removal unit 5 with the fluorine compound supplied from the fluorine compound supply means 7. In FIG. 4, the mixing unit 13 is provided in a flow path communicating with the exit side of the fluorine removing unit 5, and for example, an inline mixer is preferably provided. In the mixing unit 13, the fluorine-removed sample water and the fluorine compound are mixed to prepare a reference solution. In FIG. 4, the third supply means 9 is provided as a flow path communicating with the mixing unit 13 and the measurement unit 1, and supplies the reference liquid to the measurement unit 1. In addition, although not shown in drawing, the mixing part 13 may be provided as a mixing tank.

The fluorine concentration measuring apparatus shown in FIG. 5 is provided with a first measuring unit 1A for analyzing sample water and a second measuring unit 1B for analyzing a reference solution as measuring units. In FIG. 5, the first measurement unit 1A includes a tank 3A in which sample water is held and a fluorine ion electrode meter 2A provided in the tank 3A, and the second measurement unit 1B is a tank in which a reference solution is held. 3B and a fluorine ion electrode meter 2B provided in the tank 3B. The tank 3A and the tank 3B are provided with discharge units for discharging the analysis target liquids (

discharge liquids

11A and 11B) after the potential measurement. In this case, the first supply unit 4 supplies sample water to the first measurement unit 1A, and the third supply unit 9 supplies fluorine removal sample water or reference solution to the second measurement unit 1B. . The measuring unit 10 calculates the value or magnitude relationship of the fluorine concentration in the sample water from the potential value of the sample water measured by the first measuring unit 1A and the potential value of the reference solution measured by the second measuring unit 1B. It becomes. If the first measuring unit 1A for analyzing the sample water and the second measuring unit 1B for analyzing the reference liquid are provided in this way, the value or magnitude relationship of the fluorine concentration of the sample water is calculated more quickly. be able to.

The fluorine concentration measuring apparatus shown in FIG. 6 is configured so that a fluorine compound solution is used as a fluorine compound to be added to a reference solution, and a solution obtained by bringing a fluorine compound solution into contact with a fluorine adsorbent is added to sample water. It is. The fluorine concentration measuring apparatus shown in FIG. 6 measures a second fluorine removing unit 14 in which a fluorine adsorbent is arranged and a fluorine compound solution is supplied, and a fluorine removing fluorine compound solution discharged from the second fluorine removing unit 14. And fourth supply means 15 for supplying to the section 1. For the details of the second fluorine removing unit 14, the description of the fluorine removing unit 5 is referred to. The 4th supply means 15 will not be specifically limited if the solution discharged | emitted from the 2nd fluorine removal part 14 can be supplied to the measurement part 1, for example, a flow path through which the said solution passes, and a liquid feeding pump is set to the said flow path What was provided, the container which conveys the said solution, etc. are mentioned. In FIG. 6, the 4th supply means 15 is shown as a flow path which connected the exit side of the 2nd fluorine removal part 14, and the measurement part 1, and the said flow path may be equipped with the liquid feeding pump. The flow path of the fourth supply means 15 may be connected to the flow path of the first supply means 4 that supplies the sample water to the measurement unit 1 and communicates with the measurement unit 1 via the flow path. In the fluorine concentration measuring apparatus shown in FIG. 6, it is easy to use a fluorine standard solution as the fluorine compound solution. In this case, the fourth supply unit 15 uses the fluorine removal standard solution discharged from the second fluorine removal unit 14. Is supplied to the measuring unit 1.

As described above, various embodiments of the fluorine concentration measuring apparatus of the present invention have been described with reference to FIGS. 3 to 6. However, each component of the embodiments shown in FIGS. 3 to 6 can be arbitrarily combined. is there. For example, the water intake unit 12 and the mixing unit 13 shown in FIG. 4 can be installed in other embodiments, and the configuration in which a plurality of measuring units 1 are provided as shown in FIG. As shown in FIG. 6, the second fluorine removing unit 14 can be installed in other embodiments.

The fluorine concentration measurement method of the present invention can be implemented in combination with various water treatment methods. Therefore, the present invention also provides a water treatment method that combines the fluorine concentration measurement method described above.

The water treatment method of the present invention is, for example, a water treatment method for obtaining treated water by removing at least part of fluorine ions from fluorine ion-containing water, and treating the treated water with the sample by the fluorine concentration measuring method described above. As water, the fluorine concentration in the treated water can be measured. The treated water may be, for example, treated water for the entire plant or unit operation treated water for removing fluorine. By measuring the fluorine concentration of the treated water by the fluorine concentration measuring method of the present invention, the fluorine concentration of the treated water can be measured easily and accurately. Thereby, it can be judged whether water treatment is performed appropriately and whether the quality of treated water is appropriate.

Fluorine ion-containing water is not particularly limited as long as it contains water in any form (for example, free form, salt form, complex form), and waste water generated at a power plant; iron making, steel, nonferrous metals, machinery Wastewater generated in various factories such as metal processing, plating, painting, electronic parts, glass, cement, etc .; landfill leachate; organic wastewater such as sewage, human waste, and livestock manure; process wastewater of various plants. In addition, it may be environmental water such as river water, lake water, groundwater, seawater and the like.

The treatment for removing at least a part of the fluorine ions from the fluorine ion-containing water may be performed mainly for the purpose of removing the fluorine ions, or the fluorine ions may be removed as a secondary. As a treatment method for the purpose of removing fluorine, for example, a method of solid-liquid separation treatment by adding a calcium compound such as slaked lime or calcium chloride, a method of solid-liquid separation treatment by addition of an aluminum compound such as sulfate band or aluminum chloride, Methods for solid-liquid separation by adding magnesium compounds such as magnesium sulfate and magnesium hydroxide, methods for adsorption removal using alumina-based adsorbent, ferritic iron-based adsorbent, zirconium-based adsorbent, cerium-based adsorbent, etc. Can be mentioned.

The water treatment method of the present invention is also a water treatment method for obtaining treated water by removing at least a part of fluorine ions from fluorine ion-containing water, wherein fluorine in fluorine ion-containing water is obtained by the fluorine concentration measuring method described above. You may measure a density | concentration. By measuring the fluorine concentration in fluorine ion-containing water using the fluorine concentration measuring method of the present invention, water treatment can be performed under appropriate conditions. For example, when adding a chemical such as the calcium compound, aluminum compound, or magnesium compound described above to fluorine ion-containing water and performing a treatment to remove at least a part of the fluorine ions, the fluorine ion-containing water is used as the sample water. By determining the addition amount of the drug based on the fluorine concentration measurement result of the fluorine ion-containing water, an appropriate amount of the drug can be added and the fluorine removal treatment can be performed efficiently. Alternatively, when the fluorine ion-containing water is introduced into a fluorine adsorption tower filled with a fluorine adsorbent and at least a part of the fluorine ions is removed, the fluorine ion-containing water is used as sample water. The fluorine ion-containing water may be diluted based on the fluorine concentration measurement result. In this case, by determining the dilution rate based on the fluorine concentration measurement result of the fluorine ion-containing water, the fluorine removal treatment in the fluorine adsorption tower is suitably performed, and the fluorine concentration of the treated water discharged from the fluorine adsorption tower is appropriately set. Can be controlled.

The water treatment method of the present invention may measure both treated water and treated water using the fluorine concentration measurement method of the present invention. In this case, by measuring the fluorine concentration of the water to be treated and the treated water by the fluorine concentration measuring method of the present invention, it is possible to perform water treatment under appropriate conditions and verify whether the treatment has been properly performed under those conditions. can do. The water treatment method of the present invention may measure intermediate treated water in the middle of obtaining treated water from the treated water using the fluorine concentration measuring method of the present invention.

The present invention also provides a water treatment apparatus that obtains treated water by removing at least part of fluorine ions from fluorine ion-containing water, and also includes a water treatment apparatus equipped with the fluorine concentration measuring apparatus of the present invention. The water treatment apparatus of the present invention is preferably capable of carrying out the water treatment method described above, and for example, preferably has a fluorine removal tank that holds fluorine ion-containing water and includes a chemical addition means. Examples of the agent to be added include the above-described calcium compound, aluminum compound, magnesium compound, and the like. Examples of the chemical addition means include a chemical pump and a feeder. The water treatment apparatus of the present invention may have a fluorine adsorption tank or a fluorine adsorption tower in which a fluorine adsorbent is disposed. As the fluorine adsorbent, an alumina-based adsorbent, a ferrite iron-based adsorbent, a zirconium-based adsorbent An adsorbent, a cerium-based adsorbent, or the like can be used.

The water treatment apparatus of the present invention may be one that collects fluorine ion-containing water as sample water, may be one that collects treated water as sample water, or one that collects both. Good. Further, intermediate treated water in the middle of obtaining treated water from treated water may be collected as sample water.

FIG. 7 shows an example of the water treatment apparatus of the present invention. The water treatment apparatus shown in FIG. 7 is an apparatus example in which a plurality of fluorine adsorption towers are connected in series. As the fluorine adsorption tower, a first adsorption tower 21 and a second adsorption tower 22 are provided, and a series connection channel 24 is provided in communication with the outlet side of the first adsorption tower 21 and the inlet side of the second adsorption tower 22, Thereby, the 1st adsorption tower 21 and the 2nd adsorption tower 22 are connected in series. Fluorine ion-containing water (treated water) 31 is first introduced into the first adsorption tower 21 through the treated water flow path 23 provided in communication with the inlet side of the first adsorption tower 21, and the first adsorption tower 21. The intermediate treated water 32 that is the effluent from the water is introduced into the second adsorption tower 22 through the series connection flow path 24, and passes through the treated water flow path 25 provided in communication with the outlet side of the second adsorption tower 22. Treated water 33 is obtained.

In the water treatment apparatus shown in FIG. 7, at least one of fluorine ion-containing water 31, intermediate treatment water 32, and treatment water 33 can be used as sample water introduced into the fluorine concentration measurement apparatus. For example, by measuring the fluorine concentration of the fluorine ion-containing water 31, the fluorine concentration of the fluorine ion-containing water 31 is adjusted to a concentration that can be suitably processed by the first adsorption tower 21 and the second adsorption tower 22. Can do. That is, when the fluorine concentration of the fluorine ion-containing water 31 is too high, the fluorine concentration of the fluorine ion-containing water 31 can be adjusted by diluting with water. By measuring the fluorine concentration of the intermediate treated water 32, it is possible to appropriately determine the timing of replacement or regeneration treatment of the fluorine adsorbent disposed in the first adsorption tower 21. By measuring the fluorine concentration in the treated water 33, it is confirmed that the fluorine adsorption treatment is suitably performed by the first adsorption tower 21 and the second adsorption tower 22, and the fluorine disposed in the second adsorption tower 22. The timing of replacement or regeneration processing of the adsorbent can be appropriately determined.

When measuring the fluorine concentrations of the fluoride ion-containing water 31, the intermediate treated water 32, and the treated water 33, a reference solution may be prepared for each measurement of each sample water, but the property variation of the fluoride ion-containing water 31 is small. In this case, the reference solution can be shared by the fluorine ion-containing water 31, the intermediate treated water 32, and the treated water 33. Further, when the fluorine concentration of the treated water 33 is sufficiently low, the treated water 33 can be used as a reference solution, and the fluorine ion-containing water 31 and the intermediate treated water 32 can be used as sample water.

The present invention can be used for measurement of fluorine ion concentration in various wastewaters and environmental waters.

This application claims the benefit of priority based on Japanese Patent Application No. 2018-097024 filed on May 21, 2018. The entire contents of the specification of Japanese Patent Application No. 2018-097024 filed on May 21, 2018 are incorporated herein by reference.

DESCRIPTION OF

SYMBOLS

1,1A, 1B: Measuring

part

2,2A, 2B: Fluorine ion electrode meter 4: 1st supply means 5: Fluorine removal part 6: 2nd supply means 7: Fluorine compound supply means 9: 3rd supply means 10:

Calculation Part

11, 11A, 11B: Discharged liquid 12: Water intake part 13: Mixing part 14: Second fluorine removing part 15: Fourth supply means 21: First adsorption tower 22: Second adsorption tower 23: Water to be treated 24: Series connection channel 25: Treated water channel 31: Fluorine ion-containing water 32: Intermediate treated water 33: Treated water

Claims

A step of measuring the potential of the sample water with a fluorine ion electrode meter to obtain a potential value P;
Contacting the sample water with a fluorine adsorbent to obtain a fluorine-removed sample water;
Adding a fluorine compound to the fluorine removal sample water to prepare a reference solution having a fluorine concentration of C1,
Measuring the potential of the reference solution with a fluorine ion electrode meter to obtain a potential value P1,
And comparing the potential value P with the potential value P1 to determine the magnitude relationship of the fluorine concentration of the sample water with the fluorine concentration C1.
A step of measuring the potential of the sample water with a fluorine ion electrode meter to obtain a potential value P;
Contacting the sample water with a fluorine adsorbent to obtain a fluorine-removed sample water;
Adding a fluorine compound to the fluorine removal sample water to prepare a first reference solution having a fluorine concentration of C1,
Preparing a second reference solution having a fluorine concentration C2 with or without adding a fluorine compound to the fluorine-removed sample water;
Measuring the potential of the first reference solution with a fluorine ion electrode meter to obtain a potential value P1,
Measuring the potential of the second reference solution with a fluorine ion electrode meter to obtain a potential value P2,
Using the fluorine concentrations C1 and C2 and the potential values P1 and P2 to create a calibration curve representing the correlation between the fluorine concentration and the potential value;
And a step of calculating a fluorine concentration of the sample water corresponding to the potential value P based on the calibration curve.
The fluorine concentration measuring method according to claim 1 or 2, wherein a fluorine standard solution having a known fluorine concentration is used as the fluorine compound added to the fluorine removal sample water in the step of preparing the reference solution.
In the step of obtaining the potential value P, a fluorine removal standard solution after contacting the fluorine standard solution with a fluorine adsorbent is added to the sample water, and the potential of the obtained solution is measured by a fluorine ion electrode meter. Item 4. The method for measuring fluorine concentration according to Item 3.
The method for measuring a fluorine concentration according to any one of claims 1 to 4, wherein the ionic strength of the sample water is 0.05 mol / L to 3.5 mol / L.
The fluorine concentration measuring method according to any one of claims 1 to 5, wherein the sample water is flue gas desulfurization wastewater discharged from flue gas desulfurization equipment.
A measurement unit equipped with a fluorine ion electrode meter;
First supply means for supplying sample water to the measurement unit;
A fluorine removal part in which a fluorine adsorbent is disposed;
Second supply means for supplying sample water to the fluorine removing unit;
Fluorine compound supply means for adding a fluorine compound to the fluorine removal sample water discharged from the fluorine removal unit and providing a reference solution;
Third supply means for supplying the fluorine-removed sample water or the reference liquid to the measurement unit;
An apparatus for measuring a fluorine concentration, comprising: an arithmetic unit that calculates a value or magnitude relationship of a fluorine concentration in the sample water from the potential value of the sample water and the reference solution measured by the measuring unit.
The fluorine concentration according to claim 7, further comprising a mixing unit that prepares a reference solution by mixing the fluorine-removed sample water discharged from the fluorine-removing unit and the fluorine compound supplied from the fluorine compound supply unit. measuring device.
The fluorine concentration measuring device according to claim 8, wherein the mixing unit is provided in a flow path communicating with the outlet side of the fluorine removing unit.
As the measurement unit, a first measurement unit for analyzing the sample water and a second measurement unit for analyzing the reference solution are provided,
The first supply means supplies the sample water to the first measurement unit,
The fluorine concentration measuring apparatus according to any one of claims 7 to 9, wherein the third supply means supplies the fluorine removal sample water or the reference liquid to the second measurement unit.
The fluorine concentration measuring device further includes a water intake unit that receives the sample water,
As the first supply means, there is provided a first supply flow path communicating with the intake portion and the inlet side of the measurement portion,
The fluorine concentration measuring device according to any one of claims 7 to 10, wherein a second supply channel communicating with the water intake unit and the inlet side of the fluorine removing unit is provided as the second supply unit.
The fluorine concentration measuring device according to any one of claims 7 to 11, wherein a fluorine standard solution having a known fluorine concentration is used as the fluorine compound.
The fluorine concentration measuring device further includes a second fluorine removing unit in which a fluorine adsorbent is disposed and the fluorine standard solution is supplied;
The fluorine concentration measuring apparatus according to claim 12, further comprising: a fourth supply unit that supplies the fluorine removal standard solution discharged from the second fluorine removal unit to the measurement unit.
A water treatment method for obtaining treated water by removing at least part of fluorine ions from fluorine ion-containing water,
A water treatment method, wherein the fluorine concentration in the treated water is measured using the treated water as the sample water by the fluorine concentration measuring method according to any one of claims 1 to 6.
A water treatment method for removing at least part of fluorine ions by adding a chemical to water containing fluorine ions,
The fluorine concentration measurement method according to any one of claims 1 to 6, wherein fluorine ion-containing water is used as the sample water, and the fluorine concentration in the fluorine ion-containing water is measured. Based on the measurement result, the fluorine ion-containing water is measured. A water treatment method characterized by determining the amount of the chemical added to water.
A water treatment method for introducing fluorine ion-containing water into a fluorine adsorption tower packed with a fluorine adsorbent and removing at least a part of the fluorine ions,
The fluorine concentration measurement method according to any one of claims 1 to 6, wherein the fluorine ion-containing water is used as the sample water, and the fluorine concentration in the fluorine ion-containing water is measured. Based on the measurement result, the fluorine ion-containing water is measured. A water treatment method comprising diluting water.
A water treatment apparatus for obtaining treated water by removing at least a part of fluorine ions from fluorine ion-containing water,
A water treatment apparatus comprising the fluorine concentration measuring apparatus according to any one of claims 7 to 13.